The problematics of genetics and the Aryan issue
To brandish genetic studies as the clincher to the Aryan debate is hasty, if not misplaced
Migrations out of India are not factored in, although there are clear archaeological trails present The Aryan debate has involved thorny linguistic, textual, archaeological issues which need to be addressed
Tony Joseph’s article (“How genetics is settling the Aryan migration debate,” June 17) heavily leans on two recent studies (which I will refer to after their first author: “Silva et al.” and “Reich et al.”) but conceals important methodological issues.
Indeed, most genetic studies suffer from shortcomings and flaws, and the larger public should be all the more aware of this problematics as they come to us in a scientific garb; actually, they are scientific only in part.
Silva et al.’s study mainly revisited older samples with new techniques; though it stressed India’s “remarkable genetic diversity” and “very complex history”, its data set of some 2,400 samples, which left out thousands of communities, was inadequate.
Such was also the case of Reich et al.’s construct of Ancestral North Indians (ANI) and Ancestral South Indians (ASI); the study had no samples from eight major Indian States, while another eight were represented by a single population!
With such a skewed distribution, the ANI/ASI construct lacked scientific validity and was simply expected to conform to predetermined results.
Mr. Joseph found that the study “proved that most groups in India today can be approximated as a mixture of these two populations”, while it only “proved” how good scientists are apt to bungle when their theoretical framework remains amateurish. Reich et al. themselves were careful to warn that their models were “oversimplifications”, which means there are no “true ancestral populations of India”, barring the original immigration from Africa some 70,000 years ago.
A second flaw is therefore circularity. “ANI is likely to have resulted from multiple migrations,” cautions Tony Joseph, “possibly including the migration of IndoEuropean language speakers”, while Silva et al.’s paper refers to “multiple dispersals into the Subcontinent”. If so, what criteria allow us to associate one of them with “the” presumed Indo-Aryan immigration?
As Nicole Boivin, an archaeologist from Oxford University with wide experience of the Subcontinent, observed, “In reading the genetics literature on South Asia... perhaps the single most serious problem concerns the assumption, which many studies actually start with as a basic premise... that the Indo-Aryan invasions are a well-established (pre)historical reality.”
Besides, migrations out of India are not factored in, although, in the Bronze Age, there are clear archaeological trails for a Harappan presence in central Asia, the Persian Gulf and Mesopotamia.
Sustained interactions also occurred along trade networks and are bound to have complexified the genetic picture.
Why not investigate such trails in the R1a debate, instead of positing, as Silva et al. do, that “the Y-chromosome haplogroup R1a... spread with pastoralism and the Indo-European languages into South Asia”? Why should this spread be wholly unidirectional?
Another pitfall is illustrated by Silva et al.’s endorsement of another study regarding the “freezing of India’s population structure” some 1,500 years ago. Ms. Boivin noted the “problematic assumption... that caste is unchanging”, and there is indeed sound historical evidence of some amount of caste mobility; endogamy was also not always strict. India’s population has been anything but “frozen”, and genetic studies reconstructing a past picture on the basis of today’s castes are liable to err.
Silva et al. speak of the “re-peopling [of South Asia] after the Last Glacial Maximum” (about 18,000 years ago); even if there must have been migrations at the time, there is no question of “repeopling”, since substantial Palaeolithic populations thrived in many parts of the Subcontinent.
The study also naively correlates the “spread of agriculture” with a few haplogroups, suggesting that agriculture came into the Subcontinent through migrations, but good evidence exists for the indigenous spread of agriculture not only in the Northwest but independently in the Ganges valley. Silva et al. attribute the “spread of Dravidian languages” to those first farmers, while recent studies from genetics and agro-linguistics have tended to show that those languages originated in south India.
Finally, the study opines that “genetic influx from Central Asia in the Bronze Age was strongly maledriven, consistent with the patriarchal, patrilocal and patrilineal social structure attributed to the inferred pastoralist early Indo-European society”.
Again, a patriarchal social structure is “attributed” to an “inferred” pastoralist Indo-European society, and results are interpreted accordingly. Anthropologically, “pastoral” migrations that leave their womenfolk behind make no sense; a “male-dominated arrival of Indo-Aryan speakers from Central Asia” is conceivable only in the context of an aggressive military campaign, invasion and conquest (which archaeology has emphatically ruled out), not with waves of pastoral immigrations.
No definitive answers yet
To brandish this study as the final solution to the IndoEuropean problem while ignoring many others that reached vastly different conclusions reflects a personal choice.
In fact, divergences among geneticists are a useful reminder that the discipline still has much room for subjective interpretations. Twenty years hence, most of the grey areas may be settled, but we are still far from that, especially in the absence of ancient DNA from the Subcontinent.
Besides, the Aryan debate has involved thorny linguistic, textual, archaeological, b io anthropological, arch aeo astronomical issues: the Indo-European problem will be laid to rest only when a theory effectively answers all those disciplines.
Mr. Joseph is right in stating that “We are all migrants.” As regards his conclusion that “We are a multi-source civilisation, not a single-source one, drawing its cultural impulses, its tradition and practices from a variety of lineages and migration histories”, I only partly agree: Indian civilisation is something more than a khichri of ethnicons, even if they all did enrich it: culturally, it has been more a creator and a giver than a recipient, as most Indologists recognised long ago. A longer version of the article and the response can be found at http://bit.ly/AryansDebate